The present invention relates to a tub grinder that is used for grinding industrial waste, such as stumps, brush, pallets, large timbers, demolition debris, trees and limbs, lumber piles and the like into particulate material that can be easily disposed of, used as a mulch ground cover or other uses, and which has a openable cover that will intercept debris that may be ejected from the open top of the tub during use. The cover, as shown, is mounted in a unique matter so that complete covering of the tub opening can be obtained, and the cover can easily be opened for filling the tub.
In the prior art, various industrial waste tub grinders have been utilized. U.S. Pat. No. 5,419,502 shows such a device. Tub grinders have been used for grinding hay and straw for years.
The assignee of the present application developed and sold a cover or lid for a tub grinder that hinged in a different manner from the present mounting by pivotally mounting the cover along a top edge of the tub. It was used as a containment device and could be adjusted in position with a winch and cable.
Tub grinders use a rotating grinding cylinder that has hammers or flails that are positioned to extend through an opening in the floor of the tub and engage material that is in the tub. The ground material is dropped down through a screen, onto a conveyor, and then conveyed where desired for disposal.
When the tub is partially full, or is being emptied, the material in the tub is at times not sufficient to prevent chunks of material engaged by the grinding cylinder or flails to be thrown through the material outwardly through an open top of the tub. It is during these times when a cover member is desired to intercept the trajectory of chunks or objects, and prevent the chunks from being thrown into the surrounding area.
The present invention relates to a tub grinder cover that has an upright frame mounted for pivotal movement about a horizontal axis that is adjacent one side of the tub. The upright frame will tilt sideways from a generally vertical position away from the tub. In a preferred form a cover member is pivoted about a second horizontal axis at the upper end of the upright frame. Hydraulic cylinders are used for controlling the pivoting of the upright frame and the cover member about their respective mounting axis.
The cover of the present invention thus easily moves so that the cover can be moved to completely overlie the tub when desired, or moved to a position where the top of the tub is completely open for filling the tub. Additionally, various intermediate positions are possible. Changing the cover position will permit an operator to accommodate the conditions being encountered.
During transport the cover is moved to overlie the tub, and to lie over a folding elevator conveyor that is used for conveying the ground material. The elevator is folded over the top of the tub for transport or storage, and the cover overlies the folded elevator so the transport height required for the tub unit is kept low.
The tub grinders used for industrial waste are large and heavy, and are generally mounted onto semi-trailers and pulled with a truck/tractor between locations.
The present cover is formed with a framework that carries screen panels that can easily be replaced if they become damaged. The screens will permit dust to be discharged without substantial hindrance and also will filter out pieces that are carried into the air. The screen also reduces the tendency of the cover to become a xe2x80x9csailxe2x80x9d in windy conditions. The screen reduces the wind load on the cover supports. The wind can pass through easily. The angle of incident of thrown objects causes even small objects to be deflected. If any small objects do pass through the screen, the energy of the small objects is reduced.